Synthesis high coordination numbers

EXAFS analysis provided structural parameters (bond distance and coordination number) for Cu-O and Cu-Cu. The small coordination numbers of the Cu-Cu (0.9) and Cu-O bonds (2.4) indicate that the hydrothermal synthesis prohibits the growth of Cu species and produced small Cu + -oxide clusters, which did not significantly change in size after the PROX reaction [90]. CO, 5.75 x 10 4 mol adsorbed on 1 g of Cu/Ce-CTAB (0.49 CO/Cu) was present, but no C02 formation was observed. The results indicate that neither the water-gas shift reaction nor CO oxidation with lattice oxygen proceeded on the Cu/Ce-CTAB catalyst. In contrast, with 2.40 x 10 4 mol 02 adsorbed on 1 g of the fresh Cu/Ce-CTAB catalyst (0.20 02/Cu) a stoichiometric amount of C02 (0.39 C02 per Cu) was produced when this surface was subsequently exposed to CO, which suggests the high oxidation activity of the Cu+-oxide cluster species on the Ce02 surface. XRF analysis showed that the small amount... 

The mechanism of formation of DMCDeT may be supposed to be stepwise and similar to the previously described CDD synthesis. In favor of this type of mechanism it may be pointed out that during the course of reaction the coordination number around the nickel atom does not drastically vary as it would if several carbon-carbon bonds were formed simultaneously. A study of the products obtained by reaction of alkynes with a deficiency of butadiene (96) supports this stepwise mechanism and is schematically summarized in Eq. (52). It is highly improbable that four or more carbon-carbon bonds would be formed simultaneously. 

Once again, the drive for improved performance in transition metal ion-catalysed processes has continued to stimulate the synthesis of new types of organophosphine and tervalent phosphorus-ester and -amide ligands. Activity in the chemistry of heteroaromatic phosphorus ring systems and low-coordination number p -bonded systems has also remained at a high level. New mechanistic insights into the Mitsunobu reaction have been reported, and interest in synthetic applications of Staudinger/Mitsunobu procedures has continued to develop. 

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